1. Field of the Invention
The present invention relates to electronic thermometers and, more particularly, to such an electronic thermometer that is durable in use.
2. Description of the Related Art
Conventional electronic thermometers commonly have a hard casing formed from plastics and a metal probe at the tapered front end of the hard casing. Because the tapered front end of a conventional electronic thermometer is not flexible, the user must use the thermometer carefully, preventing a break in the connection area between the casing and the metal probe. In order to eliminate this problem, electronic thermometers having a flexible body portion are developed. However these electronic thermometers are still not satisfactory in function. FIGS. 1 and 2 show an electronic thermometer constructed according to Taiwan Patent Publication No. 495024. This design of electronic thermometer comprises a casing 40, a tapered tube 42 formed of hard plastics and extended from one end of the casing 40, a flexible covering 41 formed from flexible material, for example, rubber and covered on the periphery of the tapered tube 42, a metal probe 43 provided at the front end of the tapered tube 42. The casing 40 has an opening 44 for viewing the liquid crystal display 45 of the circuit board inside the casing 40. This design of electronic thermometer has drawbacks. When the front end of the electronic thermometer curved during a measuring action, the connection area 46 between the covering 41 and the metal probe 43 tends to break (see FIG. 3). Another drawback of this design of electronic thermometer is that the coarse outer surface of the covering 41 tends to be covered with dirt. It is also difficult to remove dust from the coarse outer surface of the covering 41. Further, because the casing 40 has a smooth outer surface, the electronic thermometer may slip from the user's hand easily. FIG. 4 shows an electronic clinical thermometer according to U.S. Pat. No. 5,165,798. This design of electronic clinical thermometer has a soft flexible portion 51 forwardly extended from the body 50 and terminating in a metal probe 52. This design of electronic clinical thermometer has similar drawbacks as that of the aforesaid Taiwan Patent Publication No. 495024. FIG. 5 shows an electronic thermometer constructed according to U.S. Pat. No. 6,379,039. This design of electronic thermometer comprises a rigid casing 60, a distal end portion 61 provided at the front side of the rigid casing 60, a flexible probe stem 62 provided at the front side of the distal end portion 61 to hold a metal probe (not shown). This design of electronic thermometer still has numerous drawbacks. One drawback of this design of electronic thermometer is that the distal end portion 61 tends to be covered with dirt. Another drawback of this design of electronic thermometer is that the flexible end portion 61 tends to break when curved during a measuring action. Further, because the casing 60 has a smooth outer surface, the electronic thermometer tends to slip from the user's hand.
Furthermore, conventional electronic thermometers commonly have a rigid key portion provided below the flexible press portion for switching on/off the switch when the flexible press portion depressed by the user. The arrangement of the rigid key portion greatly increases the manufacturing cost of the electronic thermometer.